Wireless communication systems, such as the 3rd Generation (3G) of mobile telephone standards and technology, are well known. An example of such 3G standards and technology is the Universal Mobile Telecommunications System (UMTS), developed by the 3rd Generation Partnership Project (3GPP) (www.3qpp.orq). The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Such macro cells utilise high power base stations (NodeBs in 3GPP parlance) to communicate with wireless Communication units within a relatively large coverage area. Typically, wireless communication units, or User Equipment (UEs) as they are often referred to in 3G parlance, communicate with a Core Network (CN) of the 3G wireless communication system via a Radio Network Subsystem (RNS). A wireless communication system typically comprises a plurality of radio network subsystems, each radio network subsystem comprising one or more cells to which UEs may attach, and thereby connect to the network. Each macro-cellular RNS further comprises a controller, in a form of a Radio Network Controller (RNC), operably coupled to the one or more Node Bs, via an lub interface.
In order to limit inter-cell interference, it is known for each base station (NodeB) to be configured with a maximum transmit power for each cell supported by that NodeB. In this manner, the transmit power of any given NodeB is limited in order to limit the interference caused by transmissions from that NodeB to neighbouring cells. Typically, the geographical coverage of a cell is typically defined by the area within which a maximum allowed path loss (MAPL) is achieved. Thus, since the path loss for a signal transmitted by the NodeB at any given location is directly affected by the transmit power for that signal, there is a significant correlation between the geographical cell coverage and the maximum transmit power of the
NodeB for that cell. In a conventional macro-cellular network, the location and geographical coverage of each macro cell is typically planned and arranged according to network requirements by the network operator. Accordingly, the maximum transmit power and MAPL for each cell supported by a NodeB is typically configured in accordance with the planned geographical coverage for that cell. Furthermore, the network operator is able to continuously monitor the coverage of the macro cells within the network, and reconfigure the maximum transmit power and MAPL of individual cells to increase or decrease the size of the cell, as required, to ensure sufficient geographical network coverage, whilst limiting the inter-cell interference.
Lower power (and therefore smaller coverage area) femto cells (or pico-cells) are a recent development within the field of wireless cellular communication systems. Femto cells or pico-cells (with the term femto cells being used hereafter to encompass pico-cells or similar) are effectively communication coverage areas supported by low power base stations (otherwise referred to as Access Points (APs)). These femto cells are intended to be able to be piggy-backed onto the more widely used macro-cellular network and support communications to UEs in a restricted, for example ‘in-building’, environment.
Typical applications for such femto APs include, by way of example, residential and commercial (e.g. office) locations, ‘hotspots’, etc, whereby an AP can be connected to a core network via, for example, the Internet using a broadband connection or the like. In this manner, femto cells can be provided in a simple, scalable deployment in specific in-building locations where, for example, network congestion at the macro-cell level may be problematic.
Significantly, such femto APs are not deployed in accordance with an overall planned network design/strategy, but rather on an ad hoc basis as required by individual users. Accordingly, parameters such as a maximum transmit power, MAPL, etc. for such femto cells are typically not configured on a planned individual basis by the network operator, but rather are typically configured according to default values determined by, say, the manufacturers of the femto APs. For example, a femto AP may be arranged to support a femto cell forming part of a particular cellular network. Thus, the network operator for that cellular network will typically define a generic/default MAPL for femto cells within that network, and the generic/default MAPL is accessible from a Management Information Base (MIB). The manufacturer of the femto AP may then configure a default maximum transmit power for the femto AP, in order to achieve a required cell coverage area within which such an MAPL for that network is achieved.
A problem with this method of configuring such parameters as the maximum transmit power and MAPL of femto cells and femto APs is that it is a very coarse, general, approach that does not take into consideration the individual circumstances and requirements for individual femto cells and their geographical locations. Furthermore, because of the variable nature of the deployment of femto cells, and the predicted large numbers of femto cells, it is not practical or even possible for a network operator or other technically competent entity to individually (re)configure the maximum transmit power, MAPL, etc. of a femto AP, and typical users are unlikely to be sufficiently competent to perform such an operation.
Thus, a need exists for a method and apparatus for enabling the dynamic configuration of femto cell parameters based on characteristics of a location of the femto access point supporting the femto cell.